Apparatus for a gun purging system

ABSTRACT

The injection of an oxidizing agent into the firing chamber of a gun tube immediately following the firing of ammunition having a combustible cartridge case provides a relatively large quantity of oxygen to facilitate combustion of any unburned or partially unburned fragments of the case. Hydrogen peroxide is uniquely suited to this application since it may be decomposed into high temperature oxygen and superheated steam; the high temperature oxygen serves as an unusually good oxidizing agent and the superheated steam provides an excellent means for cleaning the internal surfaces of the gun tube.

United States Patent [191 Graham Nov. 13, 1973 [54] APPARATUS FOR A GUN PURGING 3,665,803 5/1972 Forstein et a1 89/7 S S 1,160,778 11/1915 Smart Inventor: Alfred R. Graham, Burnt Hills, N.Y.

The United States of America as represented by the Secretary of the Army, Washington, DC.

Filed: Nov. 26, 1971 Appl. No.: 202,149

Assignee:

References Cited UNITED STATES PATENTS 5/1905 Edwards et al 89/1 E 4/1967 Dorsey, Jr. et al. 89/7 5/1961 Hudson 89/7 Primary Examiner-Samuel W. Engle Atzornzy-Harry M. Saragovitz et a1.

[57] ABSTRACT The injection of an oxidizing agent into the firing chamber of a gun tube immediately following the firing of ammunition having a combustible cartridge case provides a relatively large quantity of oxygen to facilitate combustion of any unburned or partially unburned fragments of the case. Hydrogen peroxide is uniquely suited to this application since it may be decomposed into high temperature oxygen and superheated steam; the high temperature oxygen serves as an unusually good oxidizing agent and the superheated steam provides an excellent means for cleaning the internal surfaces of the gun tube.

1 Claim, 1 Drawing Figure PATENIEDNUHS 1915 3,771,414

INVEN TOR.

A1fPEdE- [fibuhum BY 1 Q4 W 1 W 7M W ATTORNEYS BACKGROUND OF THE INVENTION The invention herein described was made in the course of or under a contract or subcontract thereunder with the Department of the Army.

This invention relates to guns of the type which fire ammunition provided with a combustible cartridge case and is particularly directed to an improved system for eliminating any unburned or partially burned fragments of the combustible case from the firing chamber.

The attributes of utilizing ammunition provided with a combustible cartridge case are well-known to persons skilled in the art. However, one of the problems incident to firing such ammunition is that unburned or partially burned fragments of the case remain in the chamber of the gun tube after firing. Obviously, this results in a hazardous condition.

results might be expected; however, because of system requirements, the quantity of air per shot is limited to approximately ft (STP).

The subject approach for solving the problem consists of introducing a strong oxidizing agent into the breech in order to burn up the residue. Such an approach is reasonable since the consumable cases are basically fuel rich, and it is known from existing data that the gases remaining in the gun after the projectile leaves are also highly fuel rich. The above hypothesis leads to the following model of the process that occurs in the breech section of a gun employing consumable case type ammunition: The grain is ignited, and at some time later, after combustion is essentially complete, the projectile leaves the gun. At that time, essentially fuel rich gases (by experimental analysis) remain in the breech section of the gun along with the remains and/or residue of the consumable case which is basically a fuel and contains no oxidizer at this time (the virgin material is fuel rich). Since neither the gases nor th remains (residue) of the case contain any oxidizing agent, combustion of the residue ceases; that is, the flame goes out. Later on, when the gun is purged with air the glowing and/or non-glowing residue does not re-ignite and hence must be blown out of the gun. It is apparent that if an oxidizing agent were continuously present during the period when the consumable case should be burning, that the case would burn up as intended.

Accordingly, it is an object of this invention to eliminate the unconsumed fragments of a combustible case after the firing of a round of ammunition.

It is a further object of the present invention .to provide a purging system for guns utilizing combustible case ammunition which is not only highly effective and efficient, but also enhances the safety of such guns during the firing thereof.

SUMMARY OF THE INVENTION It has been determined that these objects can be effectively attained by introducing a strong oxidizing agent into the breech end of a gun tube immediately following the firing of combustible case ammunition and prior to opening of the gun breech.

BRIEF DESCRIPTION OF THE DRAWING The exact nature of the invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawing which is a single schematic view of a system for injecting an oxidizing agent directly into the firing chamber of a gun.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In guns designed to fire combustible case ammunition wherein the propellant is contained in a consumable material molded and hardened into a hollow case for supporting and retaining a projectile therein, complete combustion and/or removal of the case portion does not always take place incident to firing. As above mentioned, partially burnd or unburned fragments of the combustible case remain in the chamber of the gun after firing as a result of insufficient oxygen (in either the combustion gases or the case material) to support combustion. These fragments, or residue, may or may not stick to the walls of the breech chamber but, in any event, they should be eliminated completely from the gun tube prior to the opening of the breech in order to maintain a safe condition.

It is apparent that if an oxidizing agent were continuously present during the period when the combustible case should be burning, the case would burn up as intended. One solution to the problem is through the use of hydrogen peroxide as a reactive-purge agent. Hydrogen peroxide, particularly in highly concentrated form is known to decompose into high temperature steam and oxygen in the presence of a suitable catalyst. For example, the readily available commercial percent grade of hydrogen peroxide yields high temperature gases (l360F) containing 42 percent oxygen and 58 percent steam by weight. In such a high temperature environment, there are few combustible materials which will not be rapidly and completely consumed. Furthermore, this grade of hydrogen peroxide will generate a large quantity of hot gas from a relatively small quantity of liquid thereby minimizing the space required to accommodate the system. In fact, each cubic foot of a 90 percent grade of liquid hydrogen peroxide at atmospheric pressure will generate about 5220 cubic feet of hot gas. The hot steam portion of the gas should have the further advantage of cleaning and removing carbon fro-m the interior-gun surface as a result of the water gas reaction. Either of two techniques may be employed for decomposing the hydrogen peroxide:

a. External Decomposition. The hydrogen peroxide is passed through a decomposition bed where it decomposes into a mixture of hot oxygen and stem which is then injected into the gun breech through suitable ports.

b. Internal Decomposition. The hydrogen peroxide is injected directly into the breech section of the gun (prior to complete breech pressure decay) and de- 3 composition is obtained thermally by means of the heat content of the gun gases. As shown in the drawing, wherein similar reference characters have been employed to designate corresponding parts throughout, the hydrogn peroxide is arranged to be injected directly into the firing chamber of a large caliber gun tube 12 (internal decomposition) by means of a suitable injector, in this case represented by a hole 14 in the breech end thereof. Although injection is preferably accomplished during the period of decreasing breech pressures, it can also be done after breech pressures have decreased to ambient pressure and prior to opening of the breech if the hydrogen peroxide is decomposed external to the gun tube. Storage of the peroxide is provided by a suitable tank 16 and is maintained at a specified pressure by a suitable pressure regulator 20 connected to a tank 18 of gaseous nitrogen, ln accordance with this arrangement, the hydrogen peroxide is injected directly into the breech section of the gun. In order to provide a safety measure against accidental premature decomposition of the peroxide in tank 16, the line leading therefrom is connected to a plurality of remotely operated relief valves 22 which are arranged in parallel to minimize any failure to operate due to the malfunctioning of the individual valves; In the event it is desired to completely dispose of the peroxide for any reason, a remotely operated dump valve 24 is provided in parallel with relief valves 22. A check valve 28 between gun tube 12 and control valve 26 serves to block the latter against the outward flow of the combustion gases generated in the firing chamber of gun tube 12.

Although decomposition of the hydrogen peroxide, in the system described above, has been achieved thermally (internal decomposition) within the breech, it is conceivable that other decomposition methods may be employed. For example, in addition to external decomposition technique mentioned above, another arrangement consists of encapsulating the peroxide in a cartridge which could be loaded directly behind the round of ammunition and would burst incident to high pressure upon firing the round.

Thus, there is provided a relatively simple and efficient technique for adequately purging a gun tube, following the firing of a round of ammunition having a combustible cartridge case, in a manner which will eliminate any unburned or partially burned fragments of the case as well as purge of various gases and other products normally produced during combustion of the propellant charge. The present invention successfully accomplishesthe required elimination of the case fragments by chemical means and is conducive to assembly into a prepackaged unit which can be readily stored in loaded condition. Because of its relatively light weight and size, such a unit can be readily introduced in the operating gun system in any convenient or desirable locationQTherefore, it is desired that the present inventionshall not be limited except insofar as it is made necessary by the prior art and by the spirit of the appended claims.

I claim:

1. A system for introducing a purging medium into the combination of a gun tube having a breech and combustible cartridge case ammunition disposed therein to eliminate the unburned powder residue and other combustion products formed during the firing of said ammunition, said system comprising,

means for pressurizing a quantity of hydrogen peroxide in adjacent relation to the breech end of said gun tube, and,

means for injecting a measured portion of the pressurized hydrogen peroxide into the breech of said gun tube following each firing therein ofa round of ammunition whereby the hydrogen peroxide decomposes to provide sufficient oxygen to complete the combustion of the unburned powder residue and to provide a quantity of rapidly expanding steam for flushing the remaining combustion products out of said gun tube. 

